Bathroom Plumbing Plan Re-done, Please Advise - Drawing Attached

[Bluegrass Picker]

First, I want to say that I deeply appreciate the advice and the information that is contained on this forum and I appreciate those persons who have provided the responses and information.

We're finalizing our bathroom plumbing after reading various posts here and after getting advice from a previous post. https://terrylove.com/forums/index....-line-please-check-diagram.63499/#post-470828

I'm adding a vent to the shower and then moving the drain for the new toilet (on the right) to a Y on the 3" stack below the Y for the shower.

Will the toilet drain at the bottom of the stack be OK getting its vent from the stack? That is Plan A (first diagram).

Plan B (2nd diagram) would be to add a santee above the santee that serves the shower P Trap drain and then run a 2" pipe horizontally below the floor over to the toilet drain. I would change the vertical vent pipe for the shower to a 2" vent all the way over to the stack in the bathroom.

It would be very difficult to run a 2" pipe up from the toilet and then over to the 3" stack in the bathroom due to wires and water lines etc. in the wall, and air ducts in the joists below, but if I absolutely had to, I'll make it happen somehow. That would be Plan C.

Is Plan A doable, or should I go with Plan B, Plan C, or do I need to consider an alternative solution?

Thanks for your help.

Bluegrass Picker

 

[Terry]

If this is the top floor bathroom, the 3" being a vent above the lav, then you're fine.
Trap arms are installed with santees, not wyes.
The toilet can be done with a wye, as it's a bowl designed to siphon anyway.
The lav and shower are vented to "prevent" siphoning.
The santee on the vent stack for the venting of the lav and shower gets turned upside down.
The santees for the shower and lav trap arm are upright.

 

[Sponsor]

 

[hj]

In the left hand drawing, the upper toilet flowing past the lower one COULD create a siphonic effect and pull the water out of it. There is absolutely no way you can connect the vent the way you indicate in the right hand drawing. It would have to rise 42" above the floor before you can connect it to the shower's vent.

 

[Bluegrass Picker]

If this is the top floor bathroom, the 3" being a vent above the lav, then you're fine.
Trap arms are installed with santees, not wyes.
The toilet can be done with a wye, as it's a bowl designed to siphon anyway.
The lav and shower are vented to "prevent" siphoning.
The santee on the vent stack for the venting of the lav and shower gets turned upside down.
The santees for the shower and lav trap arm are upright.

Thank you very much for your reply.

The bathroom is on the top floor (single level house with basement).

I just want to make sure that I understand correctly that the first drawing would be doable, with the toilet connected to a Y below the shower connection to the 3" main stack?

I'll be sure to turn the santee upside down where the shower vent connects to the shower vent stack. The santee for the shower will be upright and the lav arm santee is existing construction and is upright already.

Would a double Y be acceptable to connect the toilet drain and the shower drain to the 3" stack instead of two separate Y's?

Thanks again for your help and thanks for this forum.

Bluegrass Picker

 

[Bluegrass Picker]

In the left hand drawing, the upper toilet flowing past the lower one COULD create a siphonic effect and pull the water out of it. There is absolutely no way you can connect the vent the way you indicate in the right hand drawing. It would have to rise 42" above the floor before you can connect it to the shower's vent.

Thanks for your reply, HJ. Much appreciated.

Looks the right hand drawing plan B is down the drain...

Bluegrass Picker